Ovarian carcinoma in identical twins

Hereditary ovarian cancer. Heterogeneity in age at onset

BACKGROUND

Hereditary ovarian cancer (HOC) is heterogeneous, with at least three distinctive syndromes, namely, hereditary site-specific ovarian cancer, hereditary breast-ovarian cancer (HBOC) syndrome, and Lynch syndrome II. Ovarian cancer, in accord with virtually all varieties of adult onset cancer, displays an increasing incidence with advancing age; however, it shows an earlier age of onset in hereditary settings.

METHODS

Detailed medical and pathology studies were performed on extended ovarian cancer-prone pedigrees, with special attention given to age at ovarian cancer onset.

RESULTS

The age of onset of ovarian cancer is heterogeneous, wherein the average age of onset in HBOC is 52 years, in hereditary site-specific ovarian cancer it is 49 years, and in the Lynch syndrome II it is 45 years, in contrast to its occurrence in the general population, at an average age of 59 years.

CONCLUSIONS

These differences are important for the initiation of surveillance and management strategies. Age of onset of ovarian cancer differences in these several hereditary subsets are less striking than they are in the case of other integral forms of cancer in the respective syndromes, such as the breast in the HBOC syndrome. In addition, the phenomenon of extremely early age of onset of ovarian cancer occurs infrequently in HOC when compared to other forms of cancer, such as the breast in HBOC or the colon in Lynch syndrome II. Knowledge about age of onset heterogeneity in HOC may harbor important clues about etiology, pathogenesis, and cancer control.

Papillary thyroid cancer in identical twins

The cases of a set of 19-year old monozygotic twins are presented--the first report of thyroid cancer of follicular origin occurring in identical twins. This report includes a brief review of reports of cancer of various sites in twins. Several studies and reports emphasize genetic factors influencing the concurrence of cancer. Other reports downgrade the likelihood of genetic influence in cancer.

Hereditary ovarian carcinoma. Biomarker studies

Three ovarian-cancer-prone kindreds were studied, two of which contained identical twin sisters concordant for ovarian carcinoma. In one kindred, both identical twin sisters had daughters with ovarian carcinoma. In another kindred, one of the identical twin sisters had an ovarian-cancer-affected daughter. Ovarian carcinoma showed vertical transmission in all three families in a pattern consonant with an autosomal dominant mode of inheritance. Medical-genetic survey of each family included detailed questionnaires with retrieval of primary medical and pathology documents on cancer of all anatomic sites. Putative biomarker determinations included: (1) in vitro hyperdiploidy in dermal monolayer cultures; and (2) lower serum levels of alpha-L-fucosidase (less than or equal to 275 IU/ml) in all cancer-affected patients and statistically significant lower levels in 50% risk individuals when compared to spouse and published controls (P = 0.04 and P = 0.0002, respectively). These findings are discussed in context with the eventual development of a risk factor profile which, given acceptable sensitivity and specificity, would enable identification of individuals who would be prime candidates for intensive surveillance/management programs.

Is cancer communicable?

Recent developments in cancer epidemiology have led to the possibility of an exceedingly complex communicable factor(s) in cancer etiology. The transmission of such an agent(s) may require a susceptible genotype and/or other promotional events. Likely candidates which support this supposition include: Epstein-Barr virus (nasopharyngeal carcinoma, Burkitt's lymphoma, salivary gland tumor among Eskimos, X-linked lymphoproliferative syndrome of Purtilo); human T-cell leukemia virus (adult T-cell leukemia); acquired immune deficiency syndrome (AIDS), complicated by Kaposi's sarcoma (etiologic agent remains elusive, though epidemiology suggests possible infectious transmission); abnormal immune phenomena in households of Hodgkin's disease patients; and clustering of various types of cancer in spouses, the general population, and families. We have selectively reviewed the literature and evolved an etiologic hypothesis which integrates a communicable agent(s) in concert with genetic and/or environmental carcinogenic interaction which could conceivably explain a significant fraction of the total cancer burden.